When John of Patmos imagined the endtimes, he wrote out of fury at what had become of Jesus’s teachings, as the Roman Empire coopted the one true faith. The sordid world of politics had, it seemed, quickly converted something precious into something profane. The reversal of fortune was so stunning that, drawing inspiration from a line of Jewish apocalyptic thinking, John concluded that not even an exaggerated denunciation of the tragic fate of Christianity in the clutches of Rome would suffice; only a grandiose cataclysm – as he imagined it – could undo the damage. The Book of Revelation, which he wrote, is so frightening that it has terrorised readers ever since.